The Echotip Procore (Cook Medical) core biopsy needle (ETP), has been demonstrated to provide excellent efficacy for core biopsy samples. Final diagnostic yield using this needle ranges from 80-90% and appears to be significantly greater than EUS-FNA for lesions requiring histology for diagnosis. However, there is currently only limited data from prospective studies comparing EUS-FNA to EUS-FNB with the ETP needle. The investigators propose a randomized, prospective, cross-over study comparing diagnostic accuracy of EUS-FNA to EUS-FNB.